Adhesive tape or foil is often applied to cover sensitive regions of various types of semiconductor devices (e.g. semiconductor sensors) in order to protect the sensitive regions of such devices from damage at various stages of manufacture and assembly such as during testing, delivery to a customer, and soldering of the semiconductor device to a circuit board by the customer. For example, an adhesive foil is often applied to cover apertures in housings of optical sensing devices to protect the optical or active regions (e.g. photodiode or charge-coupled device arrays) of the semiconductor optical sensor chip disposed therein, or to cover apertures in the housings of pressure-sensing MEMs devices. The adhesive foil applied to optical sensing devices is typically thin enough and transparent enough to allow testing of the active regions of the optical sensor chip by an external light source with the protective foil in place.
According to conventional techniques, application of adhesive foil to such devices typically includes stamping or punching pieces having a desired shape from a continuous reel of adhesive foil using a cutting die or punch knife, and then attaching the stamped piece of adhesive foil at a desired location on the device. While such conventional techniques are generally effective, there are several drawbacks.
For example, glue or adhesive material from the adhesive foil tends to accumulate on the punch tools so that frequent cleaning is required and the punch knives become dull and require periodic replacement. Such cleaning and replacement is costly in terms of parts and labor, as well as in costs associated with downtime of the equipment. Also, such techniques are slow in that the stamping and application of the stamped piece of adhesive foil to the semiconductor device are sequential in nature, and because the application equipment must align itself with each individual semiconductor device in order to apply the piece of adhesive foil.
Additionally, stamping or punching processes often leave glue residue along the edges of the stamped piece of adhesive foil. During subsequent testing of the semiconductor device, test equipment moving in close proximity to device may contact the glue residue and peel off the piece of foil thereby exposing the device to potential contamination and potentially jamming the test equipment. Furthermore, stamping or punching processes are generally limited to circular shapes as corners of non-circular shapes are not always properly or completely punched which reduces the quality of the stamped shapes so that they may not properly adhere to the device or have excess glue residue as described above.